BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 2,911.8	$ 2,794.1
Depreciation and amortization:
Depreciation and amortization	357.5	343.6	$ 347.5
Revenues	12,161.6	11,863.9	13,136.1
Operating Income (Loss)	725.6	1,436.5	3,048.6
Amortization of intangibles and other assets	(219.8)	(193.6)	(229.5)
Net restructuring charges	(49.1)	(54.0)	(24.0)
Goodwill and Intangible Asset Impairment	(349.0)	(261.7)	0.0
Provision for income taxes	188.5	233.9	690.0
Net earnings	419.2	1,280.6	2,379.5
Net Income (Loss) Attributable to Noncontrolling Interest	(1.2)	(1.5)	(2.2)
Net earnings attributable to Laboratory Corporation of America Holdings	418.0	1,279.1	2,377.3
Operating Segments
Depreciation and amortization:
Operating Income (Loss)	1,987.6	2,414.6	3,706.6
Intersegment Eliminations
Depreciation and amortization:
Revenues	27.7	36.9	88.2
LabCorp Diagnostics [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	1,799.2	1,669.2
Depreciation and amortization:
Depreciation and amortization	236.1	227.1	238.6
Revenues	9,415.1	9,203.5	10,363.6
Operating Income (Loss)	1,591.3	2,025.5	3,205.6
Covance Drug Development [Member]
Depreciation and amortization:
Goodwill and Intangible Asset Impairment	(333.6)
Covance Drug Development [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	1,112.6	1,124.9
Depreciation and amortization:
Depreciation and amortization	112.5	112.8	106.3
Revenues	2,774.2	2,697.3	2,860.7
Operating Income (Loss)	396.3	389.1	501.0
Corporate Segment [Member]
Depreciation and amortization:
Depreciation and amortization	8.9	3.7	2.6
Operating Income (Loss)	(644.1)	(468.8)	$ (404.5)
Other countries [Member]
Segment Reporting Information [Line Items]
Property, plant and equipment, net	98.9	102.7
Other countries [Member] | LabCorp Diagnostics [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	0.0	0.0
Other countries [Member] | Covance Drug Development [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	98.9	102.7
North America
Segment Reporting Information [Line Items]
Property, plant and equipment, net	2,418.2	2,308.9
North America | LabCorp Diagnostics [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	1,799.2	1,669.2
North America | Covance Drug Development [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	619.0	639.7
Europe [Member]
Segment Reporting Information [Line Items]
Property, plant and equipment, net	394.7	382.4
Europe [Member] | LabCorp Diagnostics [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	0.0	0.0
Europe [Member] | Covance Drug Development [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 394.7	$ 382.4